<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .style1{
            background:yellow;
            width:250px;height:250px;
        }
        .style2{
            background:black;
            width:50px;height:50px;
        }
        .box{
            display: flex;
        }
        /* span:nth-of-type(2){ */
        .item:nth-child(2){
            align-self: flex-end;
        }
    
    </style>
</head>
<body>
    <div class="box style1" >
        <span class="item style2"></span>
        <span class="item style2"></span>
    </div>
</body>
<script>




</script>
</html>